Amount Of Zn Addition Research Articles

Microstructure, Interfacial IMC and Wettability of Sn-0.7Cu-xZn Solder Alloy

In this study, the effect of Zinc (Zn) addition on microstructure, interfacial IMC and wettability properties of Sn-0.7Cu lead free solder alloy was investigated. The addition of 0.5, 1.0 and 1.5 wt.% Zn into Sn-0.7Cu was developed by using conventional casting method. The result revealed that the addition of Zn has refined the β-Sn phase. The thickness of interfacial IMC decreased with 0.5 wt.% and 1.0 wt.% Zn addition but increased after 1.5 wt.% of Zn was added. The wettability of Sn-0.7Cu also improved by the Zn addition. It can be concluded that a small amount of Zn addition up to 1.0 wt.% decreased the thickness of IMC and improved the wettability. However, when 1.5 wt.% Zn was added, the interfacial IMC and wettability become worse.

Effects of high Zn content on the microstructure and mechanical properties of Al–Zn–Cu gravity-cast alloys

In this paper, the effects of Zn on the microstructural evolution, hardness, and various characteristics of Al–20–45Zn–3Cu alloys were investigated. High-strength Al–Zn–Cu alloys (>450MPa) were fabricated by gravity casting without melt modification or heat treatment (i.e. T4–T6). Al-based alloys containing more than 20% Zn were designed for the gravity-casting process. In terms of the microstructure, as the amount of Zn addition in the alloys increased, the α-phase size decreased and the α+η non-equilibrium solidification-phase fraction increased. A complex network of eutectoid α+η, supersaturated η, and Cu-related intermetallic particles formed in the grain boundary regions. In addition, increasing the Zn content improved the mechanical properties of the alloys but reduced their damping capacity and toughness. The fractographic examination of the fracture surfaces indicated that the Al–Zn–Cu alloys with high Zn addition had fewer ductile dimple surfaces and more brittle cleavage surfaces.

Effects of Zn Addition and Aging Condition on Serrated Flow in Al-Mg Alloys

The serrated flow phenomena in Al-Mg alloys with and without Zn were investigated after aging on several conditions, focusing on the role of precipitates. Al-6mass%Mg-0~3mass%Zn alloys were solution treated at 753~803K, quenched, and then aged at room temperature. Further artificial aging at 323~573K for 86.4ks was performed for some of them after natural aging for 2.6Ms. The serrated flow behavior was evaluated by tensile test. Microstructure was characterized by differential scanning calorimetry, transmission electron microscopy, atom probe tomography, and positron annihilation lifetime spectroscopy. The increase in the amount of Zn addition and the natural aging time lead to a delayed onset of serrated flow. The artificial aging at higher temperatures after natural aging, on the other hand, decreases the onset strain. A large number of small coherent Zn-Mg clusters are formed during natural aging in the Al-Mg-Zn alloys, which are transformed to the larger incoherent meta-stable precipitates during subsequent artificial aging. These results suggest that the mechanism of interfering with serrated flow is related to the vacancy trapping effect, which is enhanced by the coherent clusters.